The invention relates to an optical power divider, for use with one incoming and a plurality of outgoing glass fibers. The invention includes an imaging device, arranged on an optical axis between the incoming and outgoing glass fibers, for transmitting radiation travelling through the incoming glass fiber to the outgoing glass fibers.
Such an optical power divider is known from the article "Verzweigungseinrichtungen in mehrwelligen optischen Datennetzen" by W. Meyer, published in Mikrowellen Magazin, 2/78, pages 153-158. The power divider represented in FIG. 6 by reference numeral 8, a so-called selfoc coupler, comprises two Selfoc (trademark) lenses arranged on one axis as well as one incoming and two outgoing glass fibers which are rigidly connected to the Selfoc lenses. The Selfoc lenses are cylindrical lenses whose optical axis are the cylinder axes. These lenses have such a radial refractive-index profile that a light point situated on the entrance surface of the Selfoc lens and on the optical axis can leave a Selfoc lens of suitable length as a parallel beam. By means of a semi-transparent mirror (beam splitter) arranged between the Selfoc lenses, which mirror has been combined in a unit with the lenses, the radiation passing through the incoming glass fiber is divided between two outgoing glass fibers. However, realizing such a power divider is comparatively intricate and demands several accurate manufacturing operations.
Furthermore, so-called star couplers are also disclosed in the Meyer publication. A star coupler is a multiple power divider in which the individual glass fibers of a data network come together and the signal power applied to one transmission line is uniformly distributed among a plurality of receiving lines. In the simplest case such a multiple power divider is made of a cylindrical cladded-core rod of a few centimeters in length and approximately 1 millimeter diameter. The end faces of the individual glass fibers abut the end faces of the rod (see FIGS. 7, 8 of the Meyer publication). However, multiple power dividers of this type have considerable power losses, which lie between approximately 5 and 8 dB.